The NCEP-DOE Reanalysis 2 project is using a state-of-the-art analysis/forecast
system to perform data assimilation using past data from 1979 through the
previous year.
A large subset of this data is available from PSD in its original 4 times
daily format and as daily averages.

Please note: If you acquire NCEP-DOE Reanalysis 2
data products from PSD, we ask that you acknowledge us in your use of the
data. This may be done by including text such as
NCEP-DOE Reanalysis 2 data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at
http://www.esrl.noaa.gov/psd/ in any documents or publications using
these data. We would also appreciate receiving a copy of the relevant
publications. This will help PSD to justify keeping the
NCEP-DOE Reanalysis 2 data set freely available online in the
future. Thank you!